1. Field of the Invention
The present invention relates to connectors for joining the ends of successive lengths of pipe or conduit and/or the connecting of pipe or conduit to a bracket, flange, housing or other mounting surface wherein the connection will be exposed to axial, transverse and bending vibrations. In particular, the present invention relates to connectors for joining a pipe from an exhaust manifold in an exhaust system to a downstream exhaust pipe. The present invention also relates to pipe constructions which incorporate catalytic converter devices.
2. The Prior Art
It is known that in vehicle exhaust systems, the motor produces a significant amount of vibration in the exhaust pipes. Operation of the motor at continuous speeds for prolonged periods of time can, especially, produce what are known as harmonic vibrations which can cause significant deflections in extended lengths of exhaust pipe. Repeated deflections of the exhaust will, in turn, cause the pipe to weaken with time and, ultimately, possibly fail. Further, such harmonic vibrations may also be transmitted through the exhaust pipes to the mountings of the pipes, promoting the loosening of the mountings, which can result in the sudden displacement of one or more components of the exhaust system, with the potential for both personal injury and equipment damage.
In addition, the transmission of vibrations through the mountings of the pipes can produce additional noise transmissions to the interior of the vehicle.
In addition to the vibrations created by the motor of the vehicle, an exhaust system is also subjected to various tension, compression and bending forces which also arise during the operation of the vehicle. While individual exhaust system components might be made stronger and more massive to resist failure by fatigue, such constructions would be undesirable due to weight considerations. Further, by making individual elements stiffer, the vibrations are merely transmitted to the exhaust system mountings or other components, not reduced or eliminated. Accordingly, it is desirable to isolate the exhaust system, or at least components of the system, from such vibrations and forces.
One example of a prior art vibration decoupling connector is found in U.S. Pat. No. 5,145,215 to Udell. The Udell ""215 patent discloses a flexible vibration decoupling connector for connecting two pipe ends, wherein one pipe end insertably receives and overlaps another pipe end. A vibration absorbing damping member, typically in the form of a metal mesh member, is radially interposed between overlapping type ends. The entire connection is surrounded by an elongated bellows structure, which is sealing affixed at its ends to the respective overlapping pipes. This flexible vibration decoupling connector is thus capable of providing a fluid tight connection between two pipe ends which are decoupled with respect to the transmission of vibrations from one pipe to the other. The flexible vibration decoupling connector of the Udell ""215 patent is further capable of accommodating substantial axial relative movement between the pipe ends, as well as some relative pivoting movement of one pipe to another.
Catalytic converters have been for many years placed into the exhaust gas path of internal combustion engine driven vehicles for the purposes of reducing the harmful emissions from these vehicles. Since such catalytic converters have been in use, it has become known that for proper operation of the catalytic converters they need to operate at a relatively high temperature and it has become desirable to configure the exhaust systems of such vehicles so that the catalytic converters will be brought up to operating temperature as quickly as possible. One method for doing this is to provide an insulated (e.g., double-walled) exhaust pipe, from the outlet of the exhaust manifold, to the inlet of the converter.
In order to respond to anticipated ever increasingly stringent emissions requirements being imposed upon auto manufacturers, multi-part catalytic converter systems are being contemplated, in which one or more preliminary converter may installed far upstream in the exhaust system, perhaps even immediately downstream of the exhaust manifold, to obtain maximum advantage of the highest temperature exhaust gases, for optimal functioning of the catalytic materials in the converter. Such preliminary converters must be relatively small in size, due to the space limitations of the engine compartments of most internal combustion engine-powered vehicles. The provision of the preliminary converter is desired to permit the remaining exhaust system design configurations to be largely unchanged, so that the conventional larger converters which are presently in use, for example, typically under the floor plan under the passenger compartment of most passenger cars, need not be reconfigured, while still obtaining enhanced emissions control performance.
The placement of a preliminary converter in the exhaust system of a vehicle is problematic, however, in that the space typically would be otherwise occupied by a flexible connector that joins the exhaust pipe immediately exiting the exhaust manifold with the downstream exhaust system components typically positioned underneath the vehicle. Omission of such exhaust system vibration decouplers is not a viable alternative, for the reasons discussed at length hereinabove.
Accordingly, it is desirable to provide a flexible connector construction which permits the placement of a preliminary catalytic converter in the exhaust flow of an internal combustion engine exhaust system far upstream of the conventionally located and configured catalytic converter.
Such desirable features of the present invention will become apparent in view of the present specification, claims, and drawings.
A flexible catalytic converter apparatus, for an exhaust system of an internal combustion engine, comprising a vibration decoupling flexible connector for connecting upstream and downstream components in an exhaust system. The vibration decoupling flexible connector includes an upstream liner tube and a downstream liner tube, in which portions of the liner tubes overlap axially, a vibration damping member operably disposed between the upstream and downstream liner tubes, and a flexible sealing member sealingly connecting the upstream and downstream liner tubes, to preclude escape of exhaust gases, passing through the vibration decoupling flexible connector, to ambient atmosphere. The flexible catalytic converter also includes a catalytic converter insert, operably disposed within at least the downstream liner tube, so that, upon installation of the flexible catalytic converter apparatus into an exhaust system for an internal combustion engine, exhaust gases passing through the vibration decoupling flexible connector are constrained to pass through the catalytic converter insert, for at least partial catalytic conversion of predetermined undesirable components of the exhaust gases.
According to a preferred embodiment of the invention, the vibration damping member is an annular member.
The flexible catalytic converter may further comprise a mounting flange sealingly connected, at least indirectly, to an upstream one of the liner tubes, for mechanically and sealingly connecting the vibration decoupling flexible connector to an upstream component of an exhaust system.
Preferably, the vibration damping member is disposed between the overlapping portions of the upstream and downstream liner tubes.
Preferably, the upstream and downstream liner tubes comprise a first liner tube having a first diameter and a radially inwardly extending flange emanating from a first end thereof; and a second liner tube having a second diameter less than the first diameter, and a radially outwardly extending flange emanating from a first end thereof. Preferably, the first end of the first liner tube axially overlaps the first end of the second liner tube, so that the first end of the first liner tube, the radially inwardly extending flange, the first end of the second liner tube and the radially outwardly extending flange define a substantially enclosed annular region between the overlapping portions of the liner tubes. The first liner tube may be the upstream liner tube. Alternatively, the second liner tube may be the upstream liner tube.
The vibration damping member may be disposed within the substantially enclosed annular region. The vibration damping member may be fabricated from at least one of the following: compressed metal mesh, ceramic wool.
The flexible sealing member is preferably a longitudinally extending bellows, having at least one circumferential, radially extending corrugation.
Preferably, the catalytic converter insert comprises a substantially cylindrical body, having a plurality of passages extending therethrough, the surfaces of which have catalytic material disposed thereon, whereupon passage of exhaust gases therethrough, the exhaust gases contact the catalytic material and become chemically altered.
The catalytic converter insert is preferably positioned within the downstream liner tube, so as to be substantially mechanically decoupled from vibrations emanating from an upstream exhaust system component, when the flexible catalytic converter apparatus is attached to upstream and downstream exhaust system components.
The upstream liner tube may be substantially shorter in length than the downstream liner tube, so that upon installation of the flexible converter apparatus into an exhaust system, positioning of the catalytic converter insert in maximized proximity to the exhaust manifold of the internal combustion engine is facilitated.